Life is incredibly resilient. In April, 2019, a microscopic, multicellular species, also known as the water bear, likely made it out alive following a crash landing on the Moon’s surface by Israel’s Beresheet probe. Based on an analysis of the spacecraft’s trajectory and the composition of the device the micro-animals were stored in the chances of survival for the tardigrades… are extremely high,” reported AFP, adding that the diminutive creatures, which are under a millimeter (0.04 inches) in size, had been dehydrated to place them in suspended animation, then “encased in an epoxy of artificial amber, and should be revivable in the future.”
Resilience of Life to Cosmic Events
The world’s most indestructible of Earth’s species, tardigrades will survive until the Sun dies, according to a 2017 Oxford University collaboration, The Resilience of Life to Astrophysical Events. “Tardigrades are as close to indestructible as it gets on Earth,” the researchers reported, “but it is possible that there are other resilient species examples elsewhere in the universe. In this context there is a real case for looking for life on Mars and in other areas of the solar system in general.”
Tardigrades –the most resilient form of life on our planet, can exist for up to 30 years without food or water and endure temperature extremes up to 150 degrees Celsius–begs the question: what else is out there?
“Interplanetary Transfer of Life”
“Since the dawn of space exploration,” reports the University of Vienna, “humankind has been fascinated by survival of terrestrial life in outer space. Outer space is a hostile environment for any form of life, but some extraordinarily resistant microorganisms can survive. Such extremophiles may migrate between planets and distribute life across the Universe, underlying the panspermia hypothesis or interplanetary transfer of life.”
Resistant to Galactic & Cosmic Radiation
A recent study by the University of Vienna examined the influence of outer space on a unique microbe, Deinococcus radiodurans, on a molecular level (image below). This extremophilic bacterium can withstands the drastic influence of outer space: galactic cosmic and solar UV radiation, extreme vacuum, temperature fluctuations, desiccation, freezing, and microgravity.
In Low Earth Orbit
After one year of exposure to low Earth orbit (LEO) outside the International Space Station during the Tanpopo space Mission, researchers report that “D. radiodurans escaped morphological damage and produced numerous outer membrane vesicles. A multifaceted protein and genomic responses were initiated to alleviate cell stress, helping the bacteria to repair DNA damage and defend against reactive oxygen species. Processes underlying transport and energy status were altered in response to space exposure. D. radiodurans used a primordial stress molecule polyamine putrescine as a reactive oxygen species scavenger during regeneration from space exposure.”
Longer, Farther Journeys Possible
“These investigations help us to understand the mechanisms and processes through which life can exist beyond Earth, expanding our knowledge how to survive and adapt in the hostile environment of outer space. The results suggest that survival of D. radiodurans in LEO for a longer period is possible due to its efficient molecular response system and indicate that even longer, farther journeys are achievable for organisms with such capabilities” says Tetyana Milojevic, a head of Space Biochemistry group at the University of Vienna and a co-author of the study.
“Life is Incredibly Mutable”
Elsewhere, a team of prominent scientists at MIT and Harvard —The Search for Extraterrestrial Genomes (SETG)–are sufficiently convinced in the plausibility of panspermia that they have spent a decade developing an instrument that can isolate, detect, and classify any extant and preserved DNA or RNA-based organism. SETG will test the hypothesis that life on Mars, if it exists, may share a common ancestor with life on Earth. that can be sent to Mars and potentially detect DNA or more primitive RNA. In other words, life not only similar to that on Earth, but actually delivered long ago from Earth.
“Barely Scratched the Surface”
“We haven’t looked for [extraterrestrial] viruses specifically before because we’ve just barely started to scratch the surface of understanding them on Earth,” says Kathryn Bywaters with NASA’s Astrobiology Institute. “Previous to now, the technology and the know-how and the understanding of viruses hasn’t been at a point that we could really extrapolate that to other planetary bodies.”
Viruses –An Indirect Detection of Cellular Life
“Assuming that viruses replicate the same way in all systems, detection of a virus would be an indirect detection of cellular life,” says Kenneth Stedman, head of the Stedman Lab at Portland State University and co-chair of NASA’s Virus Focus Group, who says that finding a virus on Mars or Saturn’s Enceladus, or Jupiter’s Europa would be a revolutionary advancement in astrobiology.
The Vienna team included colleagues from Tokyo University of Pharmacy and Life Science (Japan), Research Group Astrobiology at German Aerospace Center (DLR, Cologne), Vienna Metabolomics Centre (ViMe) at the University of Vienna and Center for Microbiome Research at Medical University Graz.
Source: D. Kölbl, E. Rabbow, P. Rettberg, M. Mora, C. Moissl-Eichinger, W. Weckwerth, A. Yamagishi, T. Milojevic “Molecular repertoire of Deinococcus radiodurans after 1 year of exposure outside the International Space Station within the Tanpopo mission.” Microbiome 8, 150 (2020).
Image credit text: Space traveler Deinococcus radiodurans recovered after 1 year of exposure to low Earth orbit (LEO) outside the International Space Station during the Tanpopo space Mission. © Tetyana Milojevic
Image credit top of page and text/tardigrade: Shutterstock License